you do not need to have money saved up for a pre-approval letter, but you will have to have the funds required by the time of closing and you will have to document the source of that income. if you go FHA you can have a 100% gift of funds for downpayment from a family member, and you can negotiate for the seller to pay closing costs. if you find a home in the USDA area then you can get 0% down financing if you qualify.
you can get a pre-approval by filling in the online application at http://www.mtgcaptial-mi.com
Recommended lenders with great rates can be found at http://www.LendAnnArbor.com
Info on MSHDA and other loan programs can be found here. http://www.therealtytour.com/Buyer-Resources/Buyer-Finance/F
Feel free to contact us at http://www.SalineRealty.com if you would like to access MLS listings directly or wish further assistance.
Let me know if you need lender recommendations- some are better and faster than others. This link will provide some details about that grant:
You can always get a free approval letter.
And you can get a USDA loan without any money down if buying a home covered by USDA.
Otherwise good luck.